java.lang.Object | |
↳ | android.view.accessibility.AccessibilityNodeProvider |
This class is the contract a client should implement to enable support of a
virtual view hierarchy rooted at a given view for accessibility purposes. A virtual
view hierarchy is a tree of imaginary Views that is reported as a part of the view
hierarchy when an AccessibilityService
explores the window content.
Since the virtual View tree does not exist this class is responsible for
managing the AccessibilityNodeInfo
s describing that tree to accessibility
services.
The main use case of these APIs is to enable a custom view that draws complex content, for example a monthly calendar grid, to be presented as a tree of logical nodes, for example month days each containing events, thus conveying its logical structure.
A typical use case is to override getAccessibilityNodeProvider()
of the
View that is a root of a virtual View hierarchy to return an instance of this class.
In such a case this instance is responsible for managing AccessibilityNodeInfo
s
describing the virtual sub-tree rooted at the View including the one representing the
View itself. Similarly the returned instance is responsible for performing accessibility
actions on any virtual view or the root view itself. For example:
getAccessibilityNodeProvider( if (mAccessibilityNodeProvider == null) { mAccessibilityNodeProvider = new AccessibilityNodeProvider() { public boolean performAction(int action, int virtualDescendantId) { // Implementation. return false; } public ListfindAccessibilityNodeInfosByText(String text, int virtualDescendantId) { // Implementation. return null; } public AccessibilityNodeInfo createAccessibilityNodeInfo(int virtualDescendantId) { // Implementation. return null; } }); return mAccessibilityNodeProvider;
Constants | |||||||||||
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int | HOST_VIEW_ID | The virtual id for the hosting View. |
Public Constructors | |||||||||||
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Public Methods | |||||||||||
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Returns an
AccessibilityNodeInfo representing a virtual view,
i.e. | |||||||||||
Finds
AccessibilityNodeInfo s by text. | |||||||||||
Find the virtual view, i.e.
| |||||||||||
Performs an accessibility action on a virtual view, i.e.
|
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Inherited Methods | |||||||||||
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From class
java.lang.Object
|
The virtual id for the hosting View.
Returns an AccessibilityNodeInfo
representing a virtual view,
i.e. a descendant of the host View, with the given virtualViewId
or the host View itself if virtualViewId
equals to HOST_VIEW_ID
.
A virtual descendant is an imaginary View that is reported as a part of the view hierarchy for accessibility purposes. This enables custom views that draw complex content to report them selves as a tree of virtual views, thus conveying their logical structure.
The implementer is responsible for obtaining an accessibility node info from the pool of reusable instances and setting the desired properties of the node info before returning it.
virtualViewId | A client defined virtual view id. |
---|
AccessibilityNodeInfo
for a virtual descendant or the
host View.Finds AccessibilityNodeInfo
s by text. The match is case insensitive
containment. The search is relative to the virtual view, i.e. a descendant of the
host View, with the given virtualViewId
or the host View itself
virtualViewId
equals to HOST_VIEW_ID
.
text | The searched text. |
---|---|
virtualViewId | A client defined virtual view id which defined the root of the tree in which to perform the search. |
Find the virtual view, i.e. a descendant of the host View, that has the specified focus type.
focus | The focus to find. One of
FOCUS_INPUT or
FOCUS_ACCESSIBILITY . |
---|
Performs an accessibility action on a virtual view, i.e. a descendant of the
host View, with the given virtualViewId
or the host View itself
if virtualViewId
equals to HOST_VIEW_ID
.
virtualViewId | A client defined virtual view id. |
---|---|
action | The action to perform. |
arguments | Optional action arguments. |